1. Field of the Invention
The invention relates generally to securing a roof window sash to the roof window frame and more particularly to a detent arrangement for allowing a snap-on fit between a frame and a sash to simplify the installation of roof window and flashing components on a roof.
2. Description of the Prior Art
Roof windows are windows that are placed on the roof of a structure. Skylights are also windows placed on the roof of a structure. The typical definition of a roof window is different from a skylight in that roof windows can be opened and closed. However, for purposes of this application, including the claims of this application, the term "roof window" will be used to mean both roof windows and skylights and any other type of window that is placed on the roof of a structure. The installation of a roof window to a roof of a dwelling requires the securing of a roof window's frame to the dwelling's roof. The installation then typically requires the installation of metal flashing and/or flexible roofing membrane material adjacent to the frame but under the counterflashing on the sash. Roof windows can be placed overhead or at eye level and installed to permit a light shaft that is straight, oblique, or flared.
Presently, roof window's frames are attached to the dwelling's roof by brackets that are well known in the art. The brackets range from an angle iron to complicated configurations that are relatively expensive to manufacture. One such bracket is shown in U.S. Pat. No. 5,682,713, entitled ROTATABLE BRACKET SECURING A WINDOW FRAME TO A ROOF, which is hereby incorporated by reference.
In the building trades, roofers typically will not go inside a house. Therefore, it is advantageous to have the roof window attached from the outside. With the roof windows of the prior art, the entire sash and frame are installed at the same time since the sash is attached to the frame at the factory. This not only makes installation more difficult, it also increases the complexity of servicing if there is broken glass or a seal failure. The metal flashing and roofing membrane must be adjacent to the frame and between the frame and the sash to ensure a proper weatherproof installation. If the sash, including the counterflashing, is secured to the frame, the entire unit must be installed before the flashing and the roof membrane can be installed. The installer is then faced with the very difficult task of forcing the roofing membrane and flashing between the counterflashing of the sash and the frame. Even with the rotatable bracket, when the window frame is secured to the roof, the sash is also secured. That is, the sash is always affixed to the frame before installation.
Many installers prefer to do a "bare frame" installation (wherein the frame is installed apart from the sash) for improved waterproofing. For "bare frame" installation the installer must remove the sash from the frame and this requires an extended period of time and great care with the multiple components that are required to install these assemblies. These assemblies require the removal of numerous screws and sheet metal parts for installation. Not only does this take more time and effort, but it also risks the loss or damage to the screws and other parts. Also, the exposed screws have a potential to create weatherproofing problems.
The alternative to the "bare frame" installation is the sash and frame being installed as one unit. But as discussed above, the installation of a single fixed unit has problems with positioning of the roofing membrane and flashing between the frame and the sash.
The present invention addresses the problems associated with the prior art and provides for easy installation and weatherproofing of the frame to the roof of the dwelling and easy and quick installation of the sash and glass unit on the prepared frame.